Nutrition guidelines for children with type 1 diabetes are similar to those for the general population, and nutrition education for families of children with type 1 diabetes includes recommendations for general healthful eating and efforts to achieve and maintain optimal weight for height. Current treatment standards emphasize physiologic insulin replacement; therefore, a primary component of medical nutrition therapy in type 1 diabetes is carbohydrate estimation, as carbohydrates are the principal macronutrient affecting glycemic excursions. A major focus is on integrating the insulin regimen and carbohydrate estimation into the familys lifestyle, conforming to preferred meal routines, food choices, and physical activity patterns. Concurrently, children with type 1 diabetes are consuming diets low in fruits, vegetables, and whole grains, and high in saturated fat. Poor diet quality is particularly concerning due to the increased risk of dyslipidemia and cardiovascular disease and the high prevalence of cardiovascular risk factors recently observed in youth with diabetes. Limited research has examined relations between usual dietary intake and diabetes management in type 1 diabetes. However, there is a growing body of evidence indicating that dietary intake, particularly carbohydrate quality, may affect blood sugar control, insulin demand, and weight management. This research examines determinants of dietary intake among youth with type 1 diabetes and tests the efficacy of strategies to improve diet quality in this population. A cross-sectional study of psychosocial factors related to eating behaviors was conducted in 291 families with youth with type 1 diabetes. Data were obtained using medical record abstraction, parent-youth interview, youth self-report surveys, parent self-report surveys, youth 3-day diet records, parent food frequency questionnaire. Findings document low intake of fruit vegetables, and whole grains, and poor overall diet quality among youth with type 1 diabetes, and indicate potentially modifiable child and family determinants of dietary intake. A clinical trial tests the efficacy a family-based behavioral intervention designed to improve diet quality by promoting intake of fruit, vegetables, whole grains, legumes, nuts, and seeds. A sample of 136 families was randomized to the behavioral nutrition intervention including continuous glucose monitoring feedback or to continuous glucose monitoring feedback only. The intervention approach, which is grounded in social cognitive theory, self-regulation, and self-determination theory, integrates motivational interviewing, active learning, and applied problem-solving to target increased dietary intake of fruits, vegetables, whole grains, legumes, nuts, and seeds. Data collected include medical record abstraction, parent-youth interview, youth self-report surveys, parent self-report surveys, youth 3-day diet records, parent 3-day diet records, youth continuous glucose monitoring, youth body composition (DXA), and youth biomarkers including lipids, carotenoids, and markers of inflammation and oxidative stress. Primary outcomes include dietary intake and glycemic control.